Once an English Channel port, it now lies 1 mile (1.6 km) inland along a narrow waterway. From the 13th century on, silting of the waterway brought about Pevensey’s economic decline. The remains of the walls and towers of a Roman fort, Anderida (c. 250 ce), rank among the best extant examples of Roman building in England. After the Norman Conquest (1066) a castle was built within the Roman walls. Pop. (2001) 2,997; (2011) 3,153.